Mandrel for pipe bending machines



Nov. 5, 1963 T, w. AVERA ETAL MANDREL Foa PIPE BENDING MACHINES 3Sheets-Sheet 1 Filed Sept. 25. 1962 INVENTORS. Tre/yf /44 7L/am y. l f l/624 U 2f f 5% I M., N w

wrbi M T. w. AVERA ETAL. 3,109,477

MANDREL FOR PIPE BENDING MACHINES s sheets-sheet 2 mm m.

Nov. 5, 1963 Filed Sept. 25, 1962 //wf/ /y//////// Nov. 5, 1963 T. w.AVERA ETAL MANDREL FOR PIPE BENDING MACHINES 5 Sheets-Sheet 3% FiledSept. 25, 1962 United States Patent Oiiice 3,109,477 MANDREL FUR PEPEBENDENG MACHINES Trent W. Aver-a and Joseph A. Cunningham, Tulsa, Okla.,assignors to Curse-United Corporation, Tulsa, Okla., a corporation ofltlahoma Fiied Sept. 25, 1962, Ser. No. 226,693 16 Ciaims. (Cl. 153-63)This invention relates to the art of bending pipe and more particularlyto pipe bending apparatus in the Irature of a mandrel adapted forexpansion inside a pipe to be bent in tight engagement with the innersurface of the pipe for the purpose of supporting the latter for bendingand adapted to eX with the pipe during the bending operation so as tomaintain it smooth and cylindrical at the zone of bend.

It is the primary object of the present invention to provide a mandrelwhich may be quickly expanded against the pipe and held tightlytherewithin during the bending operation and thereupon rapidlycontracted so that the pipe may be advanced for successive bendingoperations Without loss of time, to the end that the complete bendingoperation may be completed without slow-down inteiference because of theuse of the mandrel in conjunction with the pipe bending machine.

The most important object of the instant invention is to provide anexpansible mandrel that yis fully effective in its function ofmaintaining the pipe smooth and cylindrical at the zone of bendthroughout a wide range of diftering types of pipe insofar as diameteris concerned and including pipes Whose walls differ in thickness, aswell as tensile strength and hardness of the material that makes up thewall of the pipe.

Another important object of the present invention is the provision of acollapsible pipe bending mandrel that is provided with parts whichproperly engage the pipe Wherever Iit has any tendency whatsoever tobuckle, Wrinkle, collapse, or otherwise deform improperly as aconsequence of the bending operation so that the inner surface of thepipe throughout the zone of bend remains or becomes smooth anduninterrupted as well as uniformly cylindrical throughout the length ofthe bend.

Still another important object of the instant invention is the provisionof a mandrel in the nature of an elon gated flexible body that issubstantially cylindrical throughout its length or otherwise has thesame cross sectional shape of the pipe to be bent and made in a mannerto yield or bend properly with the pipe as the latter is being bent,4while at the same time maintaining its tight grip against the pipethroughout the length of the body, with the result that the necessaryattenuation takes place in the pipe along the large radius of the bendand the essential compression takes place in the pipe throughout thesmaller radius of the bend while the pipeengaging parts of the mandrelremain in tight contact therewith.

A further oject of the present invention is to provide a. mandrel whosepipe-engaging parts bear against the pipe in a manner to avoid anypossible bulging of the pipe at various location-s Within the bend sothat bumps, depressions and other undesirable deformities are completelyavoided.

An extremely important aim of our instant invention is to provideapparatus for facilitating the bending of pipe that operates in a mannerto assure supporting engagement of the mandrel parts with the pipequickly and easily and in complete absence of interference, slow-down orineffective clamping as might otherwise be experienced if a frictional,sliding interengagement between the mandrel and the pipe were necessaryduring the expansion and contracting operation.

Yet another aim of our instant invention is to provide 31,109,477Patented Nov. 5, 1963 a mandrel wherein the forces exerted against thepipe are properly distributed, not only longitudinally, butcircurnferentially of the mandrel.

lt is contemplated that the instant invention shall have the importantaim of providing a pipe bending mandrel which combines a `powerful andtruly radial action of expansion with not only the over-all flexiblecharacteristics of the mandrel, but the resilient nature of thepipeengaging parts, all for the purpose of attaining the necessary anddesired results above enumerated.

In the drawings:

FIGURE 1 is an end elevational view of a mandrel for pipe bendingmachines made according to our present invention;

FIG. 2 is a side elevational View of the mandrelshoW- ing the same in acontracted position Within a fragment of a pipe, the latter of which isin turn illustrated schematically within certain parts of a pipe bendingmachine;

FIG. 3 is an enlarged cross-sectional view taken on line 3 3 of FIG. 2,illustrating only the mandrel, but in an expanded condition;

FIG. 4 is a crosssectional view fragmentarily illustrating one of theexpansion units or assemblies, the section being within a plane throughand parallel to the longitudinal axis of the mandrel;

FIG. 5 is an enlarged, detailed end-elevational View of one of thelbeams of the uppermost pipe support of the mandrel;

F'I'G. 6 is an enlarged, detailed, cross-sectional View through one ofthe pipe-engaging parts of one of the beams of the lower pipe support ofthe mandrel;

FIG. 7 is a cross-sectional View taken on line 7-7 of FIG. 6;

FIG. 8 is an enlarged elevational view of the drive entirely removedfrom the remaining structure of the malldrel showing that side of thedrive opposite to that seen in FIG. 2; and

FIG. 9 is essentially a top view of the drive partially in section andtaken along irregular line 9-9 in FIG. 8.

As best seen in FIG. 2 of the drawings, our expansible pipe bendingmandrel which embodies the concepts of the instant invention is in thenature of an elongated flexible body broadly designated by the numeral10 and provided with spider-like framework 12 and 14 at its ends. Body10 includes a plurality of longitudinally spaced expansion units orassemblies 16, `18 and 20 which may be of identical construction;therefore, reference may be had to FIGS. 3 and 4 of the drawings for anunderstanding of the details of the unit 18.

A housing 22 has a ring 24 closed on opposite faces thereof by a plate26 and a hollow cone 28, the latter of which has a cylinder 30 attachedthereto.

A piston 32 within the cylinder 30 has its stern 34 attached to a disc36, the latter of Which is in turn provided with a guide 38 reciprocablycarried by the plate 26.

The ring 24 carries a plurality of radially reciprocable rams orplungers 40 that are actuated by links 42 which pivotally interconnectthe plungers 404 with the disc 36. It is to be understood at thisjuncture that the details of construction of the fluid-actuated plungers46 as just above described may be varied within the spirit of theinstant invention since the construction thereof, as depicted in FIGS. 3and 4 `of the drawings, is for illustrative purposes only, showing butone manner of power actuation for the plungers 40. Within theseconcepts, therefore, it is manifest also that means other than `thepneumatic or hydraulic actuated piston 32 may be provided to supply thepower to force the plungers 40 in a radial direction outwardly from theaxes of the units 16, 18 and 20 that is coincident with the reciprocablepath of travel of the piston 32, the stem 34, the disc 36 and the guide3,8.

Each of the plungers 40 of each of the units 16, 18 and 20, regardlessof the number of plungers 40 chosen for each unit, and regardless of thenumber of expansion unitsl that are utilized in the mandrel, may beprovided with a shoe in the nature of a pad or a block, positioned tormly engage the inner surface of pipe 44 when the mandrel is expanded inthe manner illustrated by FIG. 3 of the drawings. Such expansion takesplace upon movement of the pistons 32 to the inner ends of fthecylinders 30, placing the links 42 in substantial alignment with theplungers 40. The plnngers 40 are then in substantial surroundingalignment with the disc 36 and are effectively locked against inwardmovement so that there is no need to rely substantially on fluidpressure as the means for preventing inward radial movement on the partof the plungers 40 as the result ofthe pressures which they mustwithstand during bending of the pipe 44.

All of the shoes of the mandrel which engage the pipe 44 asaforementioned may be resilient if desired but, as illustrated, thereare three types of shoes 46, 48 and Si), the shoes 46 Iand 48 all beingresilient. The shoes 50 may be solid, made, for example, from a suitablemetallic, hard rubber or plastic material. The rubber or other substancechosen for the shoes 46 and 4S should be se-v lected in light of thegreat pressures to be applied thereto and if resilient material is alsoselected for the shoes 50,v it is contempla-ted that such rubber orother material be appreciably harder and much less resilient than thematerial chosen for the shoes 46 and V48. In other words, by way ofexample, shoes may be identical if so desired.

AllV of rthe shoes 46, 48 and 5G are provided with a single centralopening 52 which receives the head of a cap screw 54 extending into theoutermost end of the corresponding plunger 40 through spacers 56. Eachof the shoes 46 and 48 has a metallic pusher plate 58 bonded to itsinnermost face and interposed between the corresponding head of bolt 5.4and spacer 56. On the other hand, it is desirable, when the shoes 50 aremade from metallic material, that their outer faces be provided with afacing `6l) bolted` or otherwise attached thereto, and made frombeliting or suitable material capable of protecting theinner surface ofpipe.44 or protective coatings that are oftentimes provided on the innerface of pipes 44. It may be, however, that facings 60 can be eliminated,depending on the natu-re of the material chosen for blocks 50.

` 'It is seen, therefore, that each of the assemblies 16, 18 and 2(3.isprovided with a continuous annular row of shoes or pads concentric totheir axes (which is coincident with the longitudinal axis of the bodysuch shoes being in side-by-side relationship and spaced only slightlywhen expanded, as shown in FIG. 3 of the drawings.

i vIn addition, the body 10 isprovided with a number of arcuate rows 62,`64, 66 and 68 of shoes 46, also concentric with the longitudinal axisof the body 10 and disposed at the top of the latter. The row 62 isinterposed between fthe annular rows 70 Vand 72, whereas the rows 64, 66and 68 are in side-by-side relationship between the two annular rows 72and 74.

Similarly,a row 76 of `shoes 50 is interposed between rows 70 and 72 anda number of rows 76, 78, 80 and 82 Y Vof shoes 50 are disposed inside-by-side relationship between the rows 72 and 74. The rows 76, 78,80 and 82 are likewise concentric with the longitudinal axis of body 10at the bottom of the latter.

-lt should be explained at this juncture that each of the annular rows70, 72 and 74 Vis made up of an arcuate row or segment ofshoes 46 inlongitudinal alignment with proximal shoes .46 of the rows 62, 64, 66and 68. In much the same manner, each of Ithe rows 70, 72 and 74includes an 4arcuate row or segment of shoes 50 disposed in longitudinalalignment with proximal shoes 50 of rows 76, 78, 80 and 82. This means,then, that the segmental lillV in covering relationship to the slots163.

4 4arcuate rows 62, 64, 66, 68, 76, 78, 80 and 82 do not have any shoescorresponding to the shoes 4S that are found in the annular rows 70, 72and 74. VThe shoes 48 are located in the rows 70, 72 and 74 betweentheir up-V permost shoes 46 and their lowermost shoes Si), thedisposition of shoes 48 being such as to move laterally in oppositedirections against the pipe, as distinguished from a general up-and-downmovement on the part of shoes 46 and Sil at the top and bottom of thepipe 44.

The arrangement is such as to present an uppermost pipe support assemblybroadly designated by the numeral 84 and a lowermost pipe supportassembly broadly designated by the numeral S6. The upper support 84includes a plurality of elongated, flexible beams 88 and 90 ofsubstantially identical nature, except only that the beams 88 'extendthe full length of body 10, whereas the beams 90 are somewhat shorter.Each of the beams 88 and 90 includes a longitudinal series or straightrow of shoes 46 in end-to-end relationship clamped together as a unit.

It is to be understood at this juncture that each of such straight rowscould comprise a single length of resilient material rather than besubdivided into individual shoes as shown. A plurality of elongated,longitudinally extending, flexible strips, preferably of metallicmaterial 92, are provided for each beam 8S and in the same manner eachbeam 90 has a number of similar strips 94. Each beam S8 is also providedwith support `structure in the nature of a strip 96 throughout itslength and a similar strip 98 is provided for each of the beams 90.Grooves 1li() extending longitudinally of the body 10 are provided inthe outermost faces of each of the shoes 46 for receiving the strips 92and, as `seen in FIG. 3, the strips 94 are similarly recessed within theouter faces of the shoes 46 of the beams 90.

The strips 96 and 3 are in the nature of bars substantially wider andsomewhat heavier than the strips 92 and 94 and extend along the innerfaces of the shoes 46 of corresponding beams 88 and 99. The clampingmeans for connecting the shoes 46 of the beams 88 and 9i) together asindivi-dual units is in the nature of a bolt `for each strip y92 |and94, respectively, such bolts 102 passing through bars 96 and 9? as bestseen in FIGS, 2 and 5, loc-ated at each Vend respectively of each beam`88 and 90'. lt is now clear that, inasmuch as the shoes 46 are clampedtogether between strips 92 and 96 and between strips 94 and 93 instraight rows extending longitudinally of the body 16, the shoes'46 ofsegmental rows 62, 64, 66 and 68 move in unison with the shoes 46 ofannular rows 70, 72

and 74 as the units 16, 18 and Ztl are in turn expanded and contractedin unison.

tlf desired, still another beam'three blocks long might be providedbeneath each of the four block beams 90.

The shoes Sil that make up the longitudinally extending beams 164 of thelower support 86 are Vinterconnected by longitudinally extending stripsor bars 106 that bear against the inner faces of the shoes 50, it beingnoted in FIG. 7 that the bars 166 are provided with elongated slots 168that extend longitudinally of the body 10 for clearing the bolts 54, andeach of the spacers 56 that Iare proximal to such enlarged openings 16Shas an external flange or enlargement 116 that bears against the bars106 It is also desirable, as noted in FIG. 3, that each of the bars 96and 98 be provided with a clearance opening 112 for bolts 54 that isslightly enlarged :to present at least a slight looseness of thecorresponding bolts `54 within the openings BecauseA of theV bars 166for each of the beams 1,04, all of theshoes Sil of the arcuate orsegmental rows 76, 78, Sil and 82 move in unison with the shoes 5l)y ofthe Y annular rows 70, 72 Vand 74 in much the same manner as abovedescribed with respect to the beams .S3 and 90 of the upper support 84.

It has been found desirable to malte .the beams 164 longer than thebeams 68; hence, still another arcuate row of shoes 50 is provided onthe bars 106 adjacent the row 70, such additional row being designatedby the numeral 114 and disposed to place the row 70 between the rows 76and L114.

The shoes 48 may be identical with the shoes 46, except only that theyare not interconnected by flexible strips and accordingly are ydevoid ofthe grooves lili). They presen-t, therefore, secondary pipe-engagingmeans and cooperate with the two primary supports 84- and 86 inproducing the desired results obtained through use of the mandrel of theinstant invention.

While the strips 92 and 96 clamp together all of the shoes 46 of therows 70, 62, 72, 64, 66, 68 and 74, the strips 94 and 98 of the beams 90connect together only the shoes 46 of the rows 78, 62, 72 and 64. On theother hand, each strip 106 of each beam 184 interconnects all of theshoes 5G of the rows 114, 78, 76, 72, 78, 80, 82 and 74.

It is now evident from FIGS. 2 and 3 that when the body 16 is fullyexpanded the inner face of pipe 44 is engaged by all of the shoes 46, 48and 58, as well as by all of the strips 92 and 94, the engagement by theshoes 50 being through their facings 60. The engagement is continuouslongitudinally of the body at the supports 84 and 86 and is continuouscircumferentially at the rows 7d, 72 and '74, inasmuch as the sets ofshoes 46., 48 and 50 of each of these annular rows present continuouspipeengaging bands for the mandrel body 10. It is also believed readilyapparent that the shoes between the outer strips and the inner barsserve as spacers for maintaining the outer pipe-engaging strips properlyspaced from the support bars therefor.

It is to be explained at this juncture that the arrangements abovedescribed may be varied considerably within the concepts of the instantinvention to suit the desires of the manufacturer and the needs ofparticular pipe bending operations. The supports 84 and 86 extendinglongitudinally of the body 1t) and generally continuous throughout itslength have been provided in such manner because of the fact that thegreatest amount of adequate support for the pipe 44 is needed at thesmall and large radii of the bend.

On the other hand, there is a lesser need for supporting the pipe 44between the upper and lower supports 84 and 86, making it possible toattain good results without need for continuing either the support 84 orthe support 86 throughout the circumference of the body 10, therebyreducing the cost of manufacture and the over-all weight of the mandrel,as well as simplifying its construction. It is also contemplated thatthe number of rows of continuous shoes, as well as the number of units16, 18 and 2d and the spacing therebetween may be varied considerablyfrom that illustrated in the drawings and above explained, dependingupon various pipe bending requirements.

Framework 12 is attached to the unit 16 by brackets 119 and similarbrackets 312i) mount the framework 14 on the unit 2o. The primarysupport for the body 10 in the pipe 44 when body 16 is contracted, asillustrated in FIG. 2, is through a pair of inclined wheels 116 on eachof the frameworks 12 and 14, respectiveiy, each wheel 116 being providedwith suitable toe-in and toe-out, as well `as height adjustment means118 for preventing the mandrel from rolling over in the pipe 44.

Fore and aft movement of the mandrel is provided by the drive,illustrated in FIGS, 2, 8 and 9. A plate 122 on the framework 14 carriesa jackshaft 124 which in turn swiugably supports an extension 126 havinga friction roller 128 adjacent its lowermost end.

A prime mover such as a fluid motor 1311 carried by plate 122 isoperably connected with the shaft 124 by chain and sprocket wheel means132 and another chain and sprocket wheel means 134 operablyinterconnects shaft 124 Vand roller means `128.

Power means which may take 4the form of a liuid piston and cylinderassembly 136 pivotally interconnects extension 126 with an upstandingarm 138 on framework 14.

The roller 128 rests loosely on the bottom of the pipe 44 during pipebending operations while the body 1t) is expanded, but when relativemovement between the mandrel and the pipe 44 is to take place theassembly 136 is actuated to compress roller 128` tightly against thepipe 44, without lifting the mandrel off the guide wheels 116, toprovide a friction or traction drive. Thereupon roller 128 is rotated byactuation of the prime mover 138. The pipe 44 is advanced from left toright, viewing FIG. 2, after each bending operation; therefore, roller128 is caused :to rotate .in a direction to maintain the mandrel insubstantially the position shown in FG. 2 with respect to the pipebending machine during the advancement of the pipe 44.

Pipe bending machines are conventionally provided with a transverselyarcuate support 140 for the pipe 44 together with a transversely concavebut longitudinally convex bending shoe 142 in diametrically opposedrelationship to the support 140x Therefore, as successive bends are madein the pipe 44 it is normally advanced several inches after each bendingoperation, whereas the mandrel itself is maintained in the samerelationship to the support 140 and the shoe .142 by operation of thedriving mechanism.

The mandrel is controlled from a remote point exteriorly of the pipe 44,the controls extending into the pipe 44 `for operable connection withfluid control valving mounted on framework 1l2. The valve that controlsthe ldownward motion of the drive roller 128 may be the same valve thatcontrols the expansion and contraction of the ma-ndrel. When the mandrelis contracted, the assembly 136 may be actuated by the same fluid thatretracts the three expanding mechanisms of the mandrel. When the mandrelis expanded, fluid in the cylinder of assembly 136 may be exhausted toatmosphere through the valve. The uid control valving for operating theprime mover 130 should also be adapted for actuation exteriorly yof thepipe 44 remote from the mandrel It is lnow apparent that when the body10 is expanded so that all parts of its periphery are tightly engagedwith the pipe `44, the latter is firmly and adequately supported forbending and, since the various pipe-engaging parts are strategicallylocated, rather sharp bends may be easily and quickly lformed withoutany collapsing or other deformations taking place at any point withinthe Zone of the bend. lMore panticularly, as bending takes place, all ofthe iflexible shoes 46 and 48 yield with the bend and at the same timeall of the strips 92, 94, `96, 98 and 106 iiex longitudinally toaccommodate not only the small radius `of the bend adjacent the shoe 142but the larger radius along the support `140.

Manifestly, the bending operation necessitates tensioning of thematerial from which the pipe 44 is made at the shoe 142, but no bucklingor wrinkling: occurs because of the support that is provided by thebeams 88 and of the support 84. These supports, made as illustrated `andabove described, eliminate all corrugations that would otherwise form atthe shoe .142 and the beams 88 and 90 perform such ifunction in a mannerto also prevent fonmation of dents, bumps, depressions and otherundesirable deformities.

By the same token, the support 86 permits the necessary attenuation ofthe material forming the pipe 44 at the larger radius 'of the bend anddoes so in a manner to avoid formation of irregularities of any naturewhatsoever in the pipe 44.

All such results take place while the mandrel effectively for-mspipe 44into a `cylindrical shape yor holds i-t cylindrical while bending takesplace. Such result occurs by the cooperative action of the shoes 48,since the continuous annular bands 70, 72 and 74 prevent the pipe 44from taking on an elliptical or other undesirable crosssectionalconfiguration.

As the large radius of `the bend is lformed along a support 140 theflexible bars 106' are permitted to bend therewith While the shoes 50maintain their tight grip with the pipe -44 because of the loose tincorporated in the support 86 by the slots 108. Similar results areobtained during flexing of .the strips 92, 94, 96 and 98` to accommodatefor the smaller radius of the bend because of the loose t provided attheopenings 112.

lrIt is to be understood, however, that the entir-e body 10 remains in.full and rrn contact with the interior of the pipe {44 during thebending operation while the two radii of the bend Vare formed, since itis not possible for any of the plungers to retract once the discs 36become `substantially aligned with the plunger, as above explained.

It is for this reason that the body '10 maintains the samecross-sectional configuration as the pipe 44 throughout the length ofthe body 10' and throughout each bending operation. lt is thereforeimpossible for the bending operation to cause the pipe 44 to take on anycross-sectional configuration other than cylindrical, and it is also notpossible for any irregularity such as Wrinkling and depression to beyformed in the pipe 44.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

l. An elongated, longitudinally flexible and resilient, transverselyexpansible mandrel adapted yfor insertion into a pipe to be bent forsupporting the pipe against distortion adjacent the zone of bendingthereof, said mandrel comprising:

a first, elongated, longitudinally flexible and resilient assembly forsupportingily engaging a longitudinal `area of the pipe -adjacent saidZone during bending of the pipe;

`a second, elongated assembly disposed in spaced, op-

posed, generally aligned, parallel relationship to said rst assembly andprovided with elongated support structure extending longitudinally ofthe second assembly;

elongated, yresiliently flexible, pipe-engaging strip means disposedoutwardly of the support structure in generally parallel, spacedrelationship there-from;

resilient spacer means disposed between said strip means and thesupportstructure along the longitudinal length thereof; Y

a pair of expansion units spaced apart longitudinally of `the assembliesand each operably coupled to said Ione assembly and to the supportstructure of the other assembly at longitudinally spaced, directlyopposed points thereon; and

means connecting theV strip means and spacer means with said supportstructure, whereby upon movement of said assemblies relatively awayIfrom each other by said units, said yone assembly and the strip meansare shifted into firm, substantially conforming, supporting. engagementwith opposed, longitudinally extending areas Iof the pipe at said zonethereof.

2. An elongated, longitudinally iiexible and resilient, transverselyexpansible mandrel adapted for insertion into a pipe to be bent forsupporting the pipe against distortion adjacent the zone of bendingthereof, said mandrel comprising:

`a rst, elongated, longitudinally flexible and resilient assembly forsupportingly engaging a longitudinal Varea of the pipe adjacent saidzone `during bending of the pipe; l y

a second, elongated assembly disposed in spaced, opposed, generallyaligned, parallel relationship to said` first assembly andV providedwith elongated, longitudinally iiexible and resilient support structureVextending longitudinally ofthe second assembly;

elongated, resiliently flexible, pipe-engagingrstrip means disposedoutwardly of the support structure in generally parallel, spacedrelationship therefrom;

` spacer means disposed between said strip means and the supportstructure along the longitudinal length thereof;

a pair of expansion units spaced apart longitudinally of the assembliesand each operably coupled to said one assembly and to the supportstructure of the other assembly at longitudinally spaced,- directlyopposed points thereon; and

means connecting the strip means and spacer means with said supportstructure, whereby upon movement of said assemblies relatively away fromeach other by said units, said one assembly and the strip means areshifted into firm, substantially conforming, supporting engagement withopposed, longitudinally extending areas of the pipe at said zonethereof.

`3. An elongated, longitudinally flexible, transversely expansiblemandrel adapted -for insertion into a pipe to be bent for supporting thepipe against distortion adja-` cent the Zone of bending thereof, saidmandrel com-` prising:

ia pair of generally circular, normally substantially axially aligned,spaced, independent expansion units each having a series of radiallymovable, circumferentially projecting members thereon;

upper and lower elongated, spaced, opposed, aligned,

l generally parallel, :pipe-engaging Vassemblies each having a pluralityof parallel, elongated, iongitudinally resiliently iexible beams carriedby members of the units in aligned relationship longitudinally of theassemblies, movable radially with respective members Vand serving tointerconnect the units with the members thereof normally lying inimaginary, generally parallel, spaced circles, said assemblies havingouter faces of transverse configuration substantially conforming to thetransverse inner surface configuration of the pipe and adapted tosupport opposed upper and low-er areas of the pipe at said zone duringbending of the pipe, said Ibeams of the upper assembly each having atleast one elongated, resiliently flexible, pipe-engaging strip thereonand each beam supporting its strip for flexing separately from theflexing of a respective beam; and

operating means coupled to said membersof the units for simultaneouslyshifting all of the members along the radial paths of travel thereofwhereby the beams of said assemblies may be radially shifted to move thestrips and the beams of said lower assembly into Ifirm, conformingengagement with said opposed upper and lower areas of the pipe.

4. A mandrel as set forth inv claim 3 wherein said operating meansincludes pneumatically operable components permitting rapid shifting ofthe members toward respective extremities of the radial paths of travelthereof.

5. In a pipe bending mandrel having an elongated body adapted forinsertion into a pipe to -be bent, said body comprising:

a Vpair of diametricaliy opposed pipe supports, each yhaving at leastone beam provided with ay row of separate pipe-engaging shoes and acontinuous, longitudinally extending, elongated element;

a pair of longitudinally spaced expansion assemblies disposed betweenthe supports for moving the latter radially outwardly in diametricallyopposite directions; Y

means connecting the elements with the assemblies for outward movementofthe elements by the assemblies;

and Y means coupling each rowV with its corresponding element fornormally holding the shoes in a straight line i extending longitudinallyof the body and for outward movement of each row of shoesV as a unit `byits element, said elements being flexible for longitudinal deformationof the beams in response to the bending of the pipe into arcs conformingto the curvatures of the bend in the pipe while the shoes are heldagainst the pipe by said assemblies.

6. In a pipe bending mandrel having an elongated body adapted forinsertion into a pipe to be bent, said body comprising:

a pair of diametrically opposed, pipe-engaging supports,

one of the supports having a plurality of side-byside, parallel beams,each beam being provided with l a continuous, longitudinally extending,elongated bar, a plurality of continuous, longitudinally extending,elongated, parallel strips spaced radially outwardly from the bar, and arow of separate shoes between the strips and the bar;

a pair of longitudinally spaced expansion assemblies disposed betweenthe supports and each provided with a plurality of radially reciprocablerams;

means connecting each bar with one ram or" each assemlbly respectivelyfor outward radial movement of the lbars by the rams; and

means connecting the strips with corresponding bars for clamping theshoes in place and normally holding the same in straight lines extendinglongitudinally of the body and for outward movement of each row as aUnit by its bar, said bars, said strips and the other of said supportsall being flexible for longitudinal deformation of 4the beams and theother support in response to the bending of the pipe into arcsconforming to the curvatures of the bend in the pipe while the supportsare held against the pipe by said assemblies.

7. A collapsible mandrel adapted for expansion inside la pipe to supportthe latter for bending and for flexing with the pipe during bending,said mandrel comprising:

a pair of spaced expansion units, each having an anfnular row of shoes,and each having mechanism for moving its yshoes radially outwardlyagainst the inner face .of the pipe;

structure interconnecting the units; and

exible means for preventing wrinkling of the pipe durling bending, saidmeans sp-anning .the distance between the units and being disposed formovement against the pipe by the mechanisms as the shoes are movedoutwardly.

8. A collapsible mandrel adapted for expansion inside a pipe to supportthe latter for bending and for flexing with the pipe during bending,said mandrel comprising:

ya ilexible body of uniform diameter throughout its length, said bodyincluding a plurality of annular rows of shoes;

a series of strips of resilient material extending longitudinally of thebody, said strips connecting the shoes of each row with the shoes ofadjacent rows; and

means for exerting radial thrust on :the shoes for forcing the shoes andthe strips against the pipe.

9. A collapsible mandrel adapted `for expansion inside a pipe to support-the latter for bending and for llexin-g with the pipe during bending,said mandrel comprising:

an elongated, llexible body of uniform. diameter throughout its length,said body including a plurality of sideby-side, longitudinallyextending, ilexible beams, each of said beams having a longitudinallyrow of adjacent pipe-engaging blocks and a resilient, pipe-engagingstrip extending longitudinally of the body, together with meansattaching the strip to the blocks, at least certain of the blocks ofeach beam having means coupled therewith for reciprocating the beamsradially of the body, said blocks being disposed to engage a substantialtarea of said pipe longitudinally thereof to provide support for thearea during bending of the the pipe at s-aid area.

10. For use in bending pipe, a mandrel for maintaining the pipe smoothand cylindrical `at the zone of bend,

while liexing with the latter therewithin during bending, said -mandrelincluding:

an elongated body having an upper and a lower longitudinal, transverselyarcuate, series of -side-by-side as- 5 semblies, each of said assembliesbeing provided with an arcuate row of pipe-engaging blocks normallyconcentric to the longitudinal axis of the body, said blocks beingdisposed to engage a substantial portion of the upper :and lower areasof the pipe;

flexible pipe-engaging elements extend-ing longitudinally of the bodyand connected to said assemblies; and a pair of -units supporting theblocks for radial movement of the latter .and lsaid elements into andout of engagement with the pipe, said units being spaced longitudinallyof the body whereby the body exes between the units yduring bending ofthe pipe. 1l. For use in bending pipe, a mandrel for maintaining thepipe smooth and cylindrical at the zone of bend, while flexing with thelatter therewithin during bending, said mandrel including:

an elongated, generally cylindrical body having a succession ofside-by-side, transversely arcuate, circumferentially extending rows ofresilient, pipe-engaging blocks throughout its length in substantiallyconcentric relationship to the longitudinal axis of the body;

means connected with each block of la spaced pair of said rows -iorshifting the same radially into tightly clamped engagement with thepipe, said blocks being disposed to engage a substantial area of thepipe; and

exible pipe-engaging means connecting the remaining rows With said pairof rows for movement therewith into and out of engagement with the pipe,whereby said remaining rows yield to the bending of the pipe in responseto deforming of said ilexible means as said pair of rows remain clampedtightly to the pipe.

l2. For use in bending pipe, a mandrel for maintaining the pipe smoothand cylindrical at the Zone of bend, while flexing with the lattertherewithin during bending, said mandrel including:

an elongated body having an arcuate series of longitudinally extending,ilexible, pipe-engaging strips, together with spaced annular rows ofpipe-engaging blocks, with said series and said rows in substantiallyconcentric relationship to the longitudinal axis of the body;

means connecting each strip with one block of each row; and

means vfor each row respectively .and circumscribed thereby for movingthe blocks and strips radially 011twardly into engagement with lthepipe.

13. For use in bending pipe, a mandrel for maintaining vthe pipe smoothand cylindrical at the zone of bend, while iiexing with the lattertherewithin during bending, said mandrel including: p

an elongated body having an arcuate series of longitudinally extending,ilexible pipe-engaging strips, together with spaced annular rows ofpipe-engaging blocks, with said series :and said rows in substantiallyconcentric relationship to the longitudinal axis of the body;

means connecting each strip with one block of each row;

means Ifor each row respectively and circumscribed thereby for movingthe blocks `and strips radially outwardly into engagement with the pipe;land means disposed in diametrically opposed relationship to said seriesand connecting said rows for limiting the extent of movement of thelatter toward and away from each other.

14. A mandrel adapted for insertion into a pipe to be bent andcomprising: l

a substantially cylindrical body having a pair of longitudinallyextending, diametrically opposed, transversely arcuate pipe supports,each having a number of rows of side-by-side, pipe-engaging blocks, one

Y 11 support having a plurality of flexible pipe-engaging strips mountedon the blocks thereof; and 'structure between the supports for movingthe same radially outwardly in opposite directions until the blocks andstrips engage the pipe.

15. In pipe-bending apparatus for insertion into a pipe which is to bebent, an expansible mandrel having the same cross-sectional shape as thepipe to be bent and including: f

a pair kof spaced expansion units each having a series of spaced ramsreciprocable simultaneously toward and away from the pipe and eachhaving a Vrow of pipe-engaging pads surrounding the same with each padsecured to the outermost end of a corresponding ram .for reciprocationtherewith, presenting a continuous band when the unit is contracted,with the pads disposed in side-by-side relationship; and

exible means bridging the units and connected therewith for engagementwith the pipe when the units are expanded.

16. In apparatus of the kind described:

an elongated mandrel having the same cross-sectional varea of a pipeinto which the same is to be inserted during bending of the latter, saidmandrel including:

a plurality of side-by-side, arcuate rows of pads having outermostpipe-engaging faces,

said rows being concentric with the longitudinal axis of the mandrel`and extending throughout the length of the latter,

certain of said rows being continuous and annular in surroundingrelationship to said axis,

the remaining rows being interposed between the continuous rows, certainof the pads being resilient and disposed to present a number ofstraight, longitudinal, side-by-side series of end-to-end pads at thetop of the mandrel, certain of the pads being disposed to present anumber of straight, longitudinal, side-by-side series of end-to-end padsat the bottom of the mandrel, each of said series of pads having aflexible bar extending longitudinally of the mandrel along the innerfaces of the pads thereof,

. each pad of each series at the bottom of the mandrel being connectedwith the corresponding bar,

i' each of said series of pads at the top of the mandrel ReferencesCited in the file of this patent UNITED STATES PATENTS 2,323,039 HillJune 29, 1943 2,339,543 Bishop Jan. 18, 1944 2,380,344 Sutton 2 July 10,1945 2,906,226 Myrick et al Sept. 29, 1959 3,043,361 Kelso -...1 v l aJuly 10, 1962

1. AN ELONGATED, LONGITUDINALLY FLEXIBLE AND RESILIENT, TRANSVERSELYEXPANSIBLE MANDREL ADAPTED FOR INSERTION INTO A PIPE TO BE BENT FORSUPPORTING THE PIPE AGAINST DISTORTION ADJACENT THE ZONE OF BENDINGTHEREOF, SAID MANDREL COMPRISING: A FIRST, ELONGATED, LONGITUDINALLYFLEXIBLE AND RESILIENT ASSEMBLY FOR SUPPORTINGLY ENGAGING A LONGITUDINALAREA OF THE PIPE ADJACENT SAID ZONE DURING BENDING OF THE PIPE; ASECOND, ELONGATED ASSEMBLY DISPOSED IN SPACED, OPPOSED, GENERALLYALIGNED, PARALLEL RELATIONSHIP TO SAID FIRST ASSEMBLY AND PROVIDED WITHELONGATED SUPPORT STRUCTURE EXTENDING LONGITUDINALLY OF THE SECONDASSEMBLY; ELONGATED, RESILIENTLY FLEXIBLE, PIPE-ENGAGING STRIP MEANSDISPOSED OUTWARDLY OF THE SUPPORT STRUCTURE IN GENERALLY PARALLEL,SPACED RELATIONSHIP THEREFROM; RESILIENT SPACER MEANS DISPOSED BETWEENSAID STRIP MEANS